1. Field of the Invention
The present invention relates compressing video data, and more specifically to an apparatus that provides assistance to a computer system in compressing a stream of video data on-the-fly, as the video data streams into the computer system.
2. State of the Art
As video data is increasingly used in computer systems in applications such as video conferencing and video recording, computer systems often cannot keep pace with the computational requirements of video data. Video data streams typically have extremely large bandwidth requirements that can tax the capabilities of even the most high-speed processor to compress the video data for storage, or for transmission across a computer network or a telephone system. This compression is typically performed by a central processing unit (CPU) in a computer system with a resulting loss in image clarity due to the failure of the CPU to keep pace with the video data. Complex scenes having many elements that are in motion represent the greatest challenge because they place a tremendous burden on the CPU during the compression and data transfer processes.
A time-consuming step in the compression of video data is to compute differences between successive video frames. A CPU typically computes a difference frame by reading a current video frame into memory and computing the difference between the current video frame and a previous video frame, which was previously stored into a memory in the computer system. Computing the difference typically involves performing an exclusive-OR operation between the current video frame and the previous video frame. In general, any function that effectively represents the difference between two successive video frames can be used with only minor modifications to the related compression algorithm. Hence, a large number of possible functions can be used to compute the difference between successive video frames.
What is needed is an apparatus or method for off-loading the time-consuming task of computing the difference between successive frames of video data from the CPU of a computer.